Bone preparation apparatus and method

ABSTRACT

A system and method for improving installation of a prosthesis. Devices include prosthesis installation tools, prosthesis assembly tools, site preparation systems, and improved power tools used in implant site preparation, the tools including a secondary motion that preferably includes an ultrasonic vibration.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation-in-part of application Ser. No.16/276,639 filed on Feb. 15, 2019; application Ser. No. 16/276,639 is aContinuation of application Ser. No. 15/398,996 filed on Jan. 5, 2017;application Ser. No. 15/398,996 is a Continuation-in-part of applicationSer. No. 15/202,434 filed on Jul. 5, 2016; and application Ser. No.15/202,434 claims the benefit of U.S. Provisional Application 62/277,294filed on Jan. 11, 2016; all of which are hereby expressly incorporatedin their entireties by reference thereto for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to bone preparation tools andprocesses such as may be used for an installation of a prosthesis, andmore specifically, but not exclusively, to improvements in prosthesisplacement and positioning through precision and efficient boneprocessing.

BACKGROUND OF THE INVENTION

The subject matter discussed in the background section should not beassumed to be prior art merely as a result of its mention in thebackground section. Similarly, a problem mentioned in the backgroundsection or associated with the subject matter of the background sectionshould not be assumed to have been previously recognized in the priorart. The subject matter in the background section merely representsdifferent approaches, which in and of themselves may also be inventions.

Earlier patents issued to the present applicant have described problemsassociated with prosthesis installation, for example acetabular cupplacement in total hip replacement surgery. See U.S. Pat. Nos. 9,168,154and 9,220,612, which are hereby expressly incorporated by referencethereto in their entireties for all purposes. Even though hipreplacement surgery has been one of the most successful operations, itcontinues to be plagued with a problem of inconsistent acetabular cupplacement. Cup mal-positioning is the single greatest cause of hipinstability, a major factor in polyethylene wear, osteolysis,impingement, component loosening and the need for hip revision surgery.

These incorporated patents explain that the process of cup implantationwith a mallet is highly unreliable and a significant cause of thisinconsistency. The patents note two specific problems associated withthe use of the mallet. First is the fact that the surgeon is unable toconsistently hit on the center point of the impaction plate, whichcauses undesirable torques and moment arms, leading to mal-alignment ofthe cup. Second, is the fact that the amount of force utilized in thisprocess is non-standardized.

In these patents there is presented a new apparatus and method of cupinsertion which uses an oscillatory motion to insert the prosthesis.Prototypes have been developed and continue to be refined and illustratethat vibratory force may allow insertion of the prosthesis with lessforce, as well, in some embodiments, of allowing simultaneouspositioning and alignment of the implant.

There are other ways of breaking down of the large undesirable,torque-producing forces associated with the discrete blows of the malletinto a series of smaller, axially aligned controlled taps, which mayachieve the same result incrementally, and in a stepwise fashion tothose set forth in the incorporated patents, (with regard to, forexample, cup insertion without unintended divergence).

An embodiment of the present invention may modify brute force bonepreparation processes and reduce bone preparation trauma by introducingvibrations to primary bone preparation motion applied by a bonepreparation implement. These vibrations can be subsonic or ultrasonic.Vibrations may affect interaction of the bone preparation implementand/or oversized implant with bone by two phenomena: (i) changing thefrictional interactions between bone and metal, and (ii) possibly,engaging bone's natural resonance frequencies (modal frequencies) whichmay make bone bend and flex.

There are two problems that may be considered independently, though somesolutions may address both in a single solution. These problems includei) undesirable and unpredictable torques and moment arms that arerelated to the primitive method currently used by surgeons, whichinvolves manually banging the mallet on an impaction plate mated to theprosthesis and ii) non-standardized and essentially uncontrolled andunquantized amounts of force utilized in these processes.

What is needed is a system and method for improving installation of aprosthesis.

BRIEF SUMMARY OF THE INVENTION

Disclosed is a system and method for improving installation of aprosthesis. The following summary of the invention is provided tofacilitate an understanding of some of the technical features related toprosthesis assembly and installation and is not intended to be a fulldescription of the present invention. A full appreciation of the variousaspects of the invention can be gained by taking the entirespecification, claims, drawings, and abstract as a whole. The presentinvention is applicable to other prosthesis in addition to acetabularcups, other modular prosthesis in addition to assembly of modularfemoral and humeral prosthesis, and to other alignment and navigationsystems in addition to referenced light guides.

An embodiment of the present invention may include axial alignment offorce transference, such as, for example, an axially sliding hammermoving between stops to impart a non-torqueing installation force. Thereare various ways of motivating and controlling the sliding hammer,including a magnitude of transferred force. Optional enhancements mayinclude pressure and/or sound sensors for gauging when a desired depthof implantation has occurred.

Other embodiments include adaptation of various devices for accurateassembly of modular prostheses, such as those that include a headaccurately impacted onto a trunnion taper that is part of a stem orother element of the prosthesis.

Still other embodiments include an alignment system to improve sitepreparation, such as, for example, including a projected visualreference of a desired orientation of a tool and then having thatreference marked and available for use during operation of the tool toensure that the alignment remains proper throughout its use, such asduring a reaming operation.

Further embodiments include enhancement of various tools, such as thoseused for cutting, trimming, drilling, and the like, with ultrasonicenhancement to make the device a better cutting, trimming, drilling,etc. device to enable its use with less strength and with improvedaccuracy.

A bone preparation tool, including a bone-processing implementconfigured to process an in-patient bone using a primary motion in aprimary mode of freedom of motion; and a motive system, coupled to thecutting implement, configured to operate the cutting implement in theprimary mode of freedom of motion and in a secondary mode of primarymode of freedom different from the primary mode of freedom wherein thesecondary mode of freedom includes an ultrasonic vibratory motion.

A method for preparing an in-patient bone, including processing, using abone-processing implement, the in-patient bone using a primary motion ina primary mode of freedom of motion for the a bone-processing implement;and concurrently operating the a bone-processing implement in asecondary motion including a secondary mode of freedom of motion;wherein the secondary mode of freedom is different than the primary modeof freedom of motion; and wherein the secondary motion includes anultrasonic vibration motion.

A bone preparation tool, including a bone-processing implementconfigured to process an in-patient bone using a primary motion in aprimary mode of freedom of motion; and a motive system, coupled to saidcutting implement, configured to operate said bone-processing implementin said primary mode of freedom of motion and in a secondary mode ofmotion, wherein said primary mode of freedom includes a non-ultrasonicmotion and wherein said secondary mode of freedom includes an ultrasonicvibratory motion superimposed on said non-ultrasonic motion.

A method for preparing an in-patient bone, including processing, using abone-processing implement, the in-patient bone using a primary motion ina primary mode of freedom of motion for said a bone-processingimplement; and concurrently operating said a bone-processing implementin a secondary motion including a secondary mode of freedom of motion;wherein said primary motion consists essentially of a non-ultrasonicmotion; and wherein said secondary motion includes an ultrasonicvibration motion.

A bone preparation tool preparing an in-patient bone with a primarymotion in a primary mode of freedom of motion, including abone-processing implement configured to process the in-patient bone withthe primary motion in the primary mode of freedom of motion; an adapterconfigured to engage and to secure said bone-processing implement; and adriver, coupled to said adapter, configured to operate saidbone-processing implement by use of said adapter, said driver operatingsaid bone-processing implement in the primary mode of freedom of motion,said driver configured to operate said bone-processing implement in asecondary motion in a secondary freedom of motion, and said driverconfigured to superimpose said motions in said modes of freedom ofmotion producing a superimposed motion, wherein the primary motion andsaid secondary motion are superimposed by said driver before anapplication of said superimposed motion to said bone-processingimplement, and wherein one of the primary motion and secondary motionincludes a driven vibratory motion.

A method for operating a bone preparation tool configured forpreparation of an in-patient bone, including producing a primary motionin a primary mode of freedom of motion; producing a secondary motion ina secondary mode of freedom of motion; superimposing said motionstogether producing a superimposed motion; and applying said superimposedmotion to a bone preparation implement of the bone preparation tool; andwherein said superimposed motion includes a driven vibratory motion.

Any of the embodiments described herein may be used alone or togetherwith one another in any combination. Inventions encompassed within thisspecification may also include embodiments that are only partiallymentioned or alluded to or are not mentioned or alluded to at all inthis brief summary or in the abstract. Although various embodiments ofthe invention may have been motivated by various deficiencies with theprior art, which may be discussed or alluded to in one or more places inthe specification, the embodiments of the invention do not necessarilyaddress any of these deficiencies. In other words, different embodimentsof the invention may address different deficiencies that may bediscussed in the specification. Some embodiments may only partiallyaddress some deficiencies or just one deficiency that may be discussedin the specification, and some embodiments may not address any of thesedeficiencies.

Other features, benefits, and advantages of the present invention willbe apparent upon a review of the present disclosure, including thespecification, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer toidentical or functionally-similar elements throughout the separate viewsand which are incorporated in and form a part of the specification,further illustrate the present invention and, together with the detaileddescription of the invention, serve to explain the principles of thepresent invention.

FIG. 1-FIG. 6 illustrate embodiments including installation of aprosthesis, including installation into living bone;

FIG. 1 illustrates an embodiment of the present invention for a slidingimpact device;

FIG. 2 illustrates a lengthwise cross-section of the embodimentillustrated in FIG. 1 including an attachment of a navigation device;

FIG. 3 illustrates a cockup mechanical gun embodiment, an alternativeembodiment to the sliding impact device illustrated in FIG. 1 and FIG.2;

FIG. 4 illustrates an alternative embodiment to the devices of FIG. 1-3including a robotic structure;

FIG. 5 illustrates an alternative embodiment to the devices of FIG. 1-4including a pressure sensor to provide feedback;

FIG. 6 illustrates an alternative embodiment to the feedback system ofFIG. 5 including a sound sensor to provide feedback for the embodimentsof FIG. 1-5;

FIG. 7-FIG. 10 illustrate prosthesis assembly embodiments including useof variations of the prosthesis installation embodiments of FIG. 1-FIG.6, such as may be used to reduce a risk of trunnionosis;

FIG. 7 illustrates a modular prosthesis and assembly tools;

FIG. 8 illustrates a femoral head to be assembled onto a trunnionattached to a femoral stem;

FIG. 9 illustrates alignment of an installation device with the femoralhead for properly aligned impaction onto the trunnion, such as anembodiment of FIG. 1-FIG. 6 adapted for this application;

FIG. 10 illustrates use of a modified vibratory system for assembly ofthe modular prosthesis;

FIG. 11-FIG. 12 illustrate an improvement to site preparation for aninstallation of a prosthesis;

FIG. 11 illustrates an environment in which a prosthesis is installedhighlighting problem with site preparation; and

FIG. 12 illustrates an alignment system for preparation and installationof a prosthesis;

FIG. 13 illustrates modified surgical devices incorporating vibratoryenergy as at least an aid to mechanical preparation;

FIG. 14-FIG. 17 illustrate a set of standard orthopedic bone preparationtools;

FIG. 14 illustrates a perspective view of a powered bone saw;

FIG. 15 illustrates a broach attachment for a powered reciprocating bonepreparation tool;

FIG. 16 illustrates a hand-operated reamer; and

FIG. 17 illustrates a set of bone preparation burrs;

FIG. 18 illustrates a side view of a first set of components for aconventional bone preparation process;

FIG. 19 illustrates a side view of a second set of components for athree-dimensional bone sculpting process that may be enabled by someembodiments of the present invention;

FIG. 20 illustrates a plan diagram of a smart tool robot;

FIG. 21 illustrates a vibratory sagittal saw;

FIG. 22 illustrates an embodiment of a vibratory sagittal sawillustrated in FIG. 21 including a set of series-coupled drivercomponents;

FIG. 23 illustrates an embodiment of a vibratory sagittal sawillustrated in FIG. 21 including a set of parallel-coupled drivercomponents;

FIG. 24 illustrates an embodiment of a vibratory sagittal sawillustrated in FIG. 21 including a set of hybrid-coupled drivercomponents;

FIG. 25 illustrates a generalized plan diagram for a first embodiment ofan ultrasonically assisted sagittal saw;

FIG. 26 illustrates a generalized plan diagram for a second embodimentof an ultrasonically assisted sagittal saw;

FIG. 27 illustrates a generalized plan diagram for a third embodiment ofan ultrasonically assisted sagittal saw; and

FIG. 28 illustrates a perspective view of a sagittal saw blade that maybe used in a vibratory/ultrasonically assisted sagittal saw such asillustrated in FIG. 13, FIG. 14, and FIG. 21-FIG. 23.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide a system and method forimproving installation of a prosthesis. The following description ispresented to enable one of ordinary skill in the art to make and use theinvention and is provided in the context of a patent application and itsrequirements.

Various modifications to the preferred embodiment and the genericprinciples and features described herein will be readily apparent tothose skilled in the art. Thus, the present invention is not intended tobe limited to the embodiment shown but is to be accorded the widestscope consistent with the principles and features described herein.

Definitions

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this general inventive conceptbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand the present disclosure, and will not be interpreted in an idealizedor overly formal sense unless expressly so defined herein.

The following definitions apply to some of the aspects described withrespect to some embodiments of the invention. These definitions maylikewise be expanded upon herein.

As used herein, the term “or” includes “and/or” and the term “and/or”includes any and all combinations of one or more of the associatedlisted items. Expressions such as “at least one of,” when preceding alist of elements, modify the entire list of elements and do not modifythe individual elements of the list.

As used herein, the singular terms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to an object can include multiple objects unless thecontext clearly dictates otherwise.

Also, as used in the description herein and throughout the claims thatfollow, the meaning of “in” includes “in” and “on” unless the contextclearly dictates otherwise. It will be understood that when an elementis referred to as being “on” another element, it can be directly on theother element or intervening elements may be present therebetween. Incontrast, when an element is referred to as being “directly on” anotherelement, there are no intervening elements present.

As used herein, the term “set” refers to a collection of one or moreobjects. Thus, for example, a set of objects can include a single objector multiple objects. Objects of a set also can be referred to as membersof the set. Objects of a set can be the same or different. In someinstances, objects of a set can share one or more common properties.

As used herein, the term “adjacent” refers to being near or adjoining.Adjacent objects can be spaced apart from one another or can be inactual or direct contact with one another. In some instances, adjacentobjects can be coupled to one another or can be formed integrally withone another.

As used herein, the terms “connect,” “connected,” and “connecting” referto a direct attachment or link. Connected objects have no or nosubstantial intermediary object or set of objects, as the contextindicates.

As used herein, the terms “couple,” “coupled,” and “coupling” refer toan operational connection or linking. Coupled objects can be directlyconnected to one another or can be indirectly connected to one another,such as via an intermediary set of objects.

The use of the term “about” applies to all numeric values, whether ornot explicitly indicated. This term generally refers to a range ofnumbers that one of ordinary skill in the art would consider as areasonable amount of deviation to the recited numeric values (i.e.,having the equivalent function or result). For example, this term can beconstrued as including a deviation of ±10 percent of the given numericvalue provided such a deviation does not alter the end function orresult of the value. Therefore, a value of about 1% can be construed tobe a range from 0.9% to 1.1%.

As used herein, the terms “substantially” and “substantial” refer to aconsiderable degree or extent. When used in conjunction with an event orcircumstance, the terms can refer to instances in which the event orcircumstance occurs precisely as well as instances in which the event orcircumstance occurs to a close approximation, such as accounting fortypical tolerance levels or variability of the embodiments describedherein.

As used herein, the terms “optional” and “optionally” mean that thesubsequently described event or circumstance may or may not occur andthat the description includes instances where the event or circumstanceoccurs and instances in which it does not.

As used herein, the term “size” refers to a characteristic dimension ofan object. Thus, for example, a size of an object that is spherical canrefer to a diameter of the object. In the case of an object that isnon-spherical, a size of the non-spherical object can refer to adiameter of a corresponding spherical object, where the correspondingspherical object exhibits or has a particular set of derivable ormeasurable properties that are substantially the same as those of thenon-spherical object. Thus, for example, a size of a non-sphericalobject can refer to a diameter of a corresponding spherical object thatexhibits light scattering or other properties that are substantially thesame as those of the non-spherical object. Alternatively, or inconjunction, a size of a non-spherical object can refer to an average ofvarious orthogonal dimensions of the object. Thus, for example, a sizeof an object that is a spheroidal can refer to an average of a majoraxis and a minor axis of the object. When referring to a set of objectsas having a particular size, it is contemplated that the objects canhave a distribution of sizes around the particular size. Thus, as usedherein, a size of a set of objects can refer to a typical size of adistribution of sizes, such as an average size, a median size, or a peaksize.

As used herein, the term “vibration” or “vibratory” refers to a seriesof mechanical displacement motions (e.g., repetitive positionalvariation or oscillations in time) about an equilibrium point thatincludes one or more axes of motion. The equilibrium point may, in turn,move, such as for impactless implantation or fixation in which theequilibrium point advances deeper into an installation site or improvedbone preparation implement sectioning a bone advancing into a sectioncut, for example, a desired depth into live bone or separation of bonesections by cutting through the bone. These vibrations are forced andresponsive to a time-varying disturbance from an oscillation engine orthe like applied, directly or indirectly, to a structure (e.g., aprosthesis or other implant) to be installed and not ancillary normalmechanical ringing of a structure in response to an application of forcewhich is typically easily damped and unable to contribute to boneremoval. The disturbance can be a periodic input, a steady-state input,a transient input, and/or a random input. A periodic input may include aharmonic or nonharmonic disturbance. Oscillation about the equilibriumpoint may be different, or similar, for each degree of freedom availablefor the vibratory motion. For example, there may be one oscillationprofile longitudinally and a second oscillation profile laterally (e.g.,perpendicular to the longitudinal axis), the two profiles generallymatching, related, derived, or independent. An amount of displacement ofan oscillation is generally less than a dimension of the implant or alength dimension of the bone preparation implement, and may be muchless, on the order of about a millimeter or less. These oscillations maybe sub-sonic, near ultrasonic, or ultrasonic. Driven vibratory motionsare “forced” when an amplitude of the motion is not appreciably degradedduring the application of those motions to a structure for its designeduse. It may be that a magnitude/amplitude of the motion remain about thesame, but a frequency may decrease and/or a power required may increaseto maintain this amplitude. What is appreciable may be dependent uponthe design considerations and constraints but may be within 50%, 25%,10%, 5%, or 1% amplitude variation during use, such as implantation orpress fit fixation of an implant into bone or an assembly of a head ontoa trunnion, for example.

Embodiments of the present invention may include one of more solutionsto the above problems. The incorporated U.S. Pat. No. 9,168,154 includesa description of several embodiments, sometimes referred to herein as aBMD3 device, some of which illustrate a principle for breaking downlarge forces associated with the discrete blows of a mallet into aseries of small taps, which in turn perform similarly in a stepwisefashion while being more efficient and safer. The BMD3 device producesthe same displacement of the implant without the need for the largeforces from the repeated impacts from the mallet. The BMD3 device mayallow modulation of force required for cup insertion based on bonedensity, cup geometry, and surface roughness. Further, a use of the BMD3device may result in the acetabulum experiencing less stress anddeformation and the implant may experience a significantly smoothersinking pattern into the acetabulum during installation. Someembodiments of the BMD3 device may provide a superior approach to theseproblems, however, described herein are two problems that can beapproached separately and with more basic methods as an alternative to,or in addition to, a BMD3 device. An issue of undesirable torques, andmoment arms is primarily related to the primitive method currently usedby surgeons, which involves manually banging the mallet on the impactionplate. The amount of force utilized in this process is alsonon-standardized and somewhat out of control.

With respect to the impaction plate and undesirable torques, anembodiment of the present invention may include a simple mechanicalsolution as an alternative to some BMD3 devices, which can be utilizedby the surgeon's hand or by a robotic machine and in some cases a smarttool robotic machine. A direction of the impact may be directed orfocused by any number of standard techniques (e.g., A-frame, C-arm ornavigation system). Elsewhere described herein is a refinement of thisprocess by considering directionality in the reaming process, incontrast to only considering it just prior to impaction. First, wepropose to eliminate the undesirable torques by delivering the impactsby a sledgehammer device or a structure (e.g., hollow cylindrical mass)that travels over a stainless rod.

FIG. 1 illustrates an embodiment of the present invention for a slidingimpact device 100, and FIG. 2 illustrates a lengthwise cross-section ofsliding impact device 100 including an attachment of a navigation device205.

Device 100 includes a moveable hammer 105 sliding axially and freelyalong a rod 110. Rod 110 includes a proximal stop 115 and distal stop120. These stops that may be integrated into rod 110 to allowtransference of force to rod 110 when hammer 105 strikes distal stop120. At a distal end 210 of rod 110, device 100 includes an attachmentsystem 215 for a prosthesis 220. For example, when prosthesis 220includes an acetabular cup having a threaded cavity 225, attachmentsystem 215 may include a complementary threaded structure that screwsinto threaded cavity 225. The illustrated design of device 100 allowsonly a perfect axial force to be imparted. The surgeon cannot deliver ablow to the edge of an impaction plate. Therefore, the design of thisinstrument is in and of itself protective, eliminating a problem of“surgeon's mallet hitting on the edge of the impaction plate” or othermis-aligned force transference, and creating undesirable torques, andhence unintentional mal-alignment of prosthesis 220 from an intendedposition/orientation.

A longitudinal axis 230 extends through the ends of rod 110. Attachmentsystem 215 aligns prosthesis 220 to axis 230 when rod 110 is coupled tothreaded cavity 225. An apex of prosthesis 220 (when it generallydefines a hollow semispherical shell) supports a structure that definesthreaded cavity 225 and that structure may define a plane 235 that maybe tangent to the apex, with plane 235 about perpendicular to axis 230when rod 110 engages prosthesis 220. Operation of device 100 is designedto deliver only axial (e.g., aligned with axis 230 and thusnon-torqueing) forces to prosthesis 220. Other embodiments illustratedin FIG. 3-FIG. 6 may be similarly configured.

FIG. 3 illustrates a cockup mechanical gun 300 embodiment, analternative embodiment to the sliding impact device illustrated in FIG.1 and FIG. 2. An alternate embodiment includes cockup mechanical gun 300that uses the potential energy of a cocked-up spring 305 to create anaxially aligned impaction force. Hammer 105 is drawn back and spring 305is locked until an operator actuates a trigger 310 to release spring 305and drive hammer 105 along rod 110 to strike distal stop 120 andtransfer an axially aligned impacting force to prosthesis 220.

Each pull of trigger 310 creates the same predetermined fixed unit offorce (some alternatives may provide a variably predetermined force).The surgeon cannot deliver a misaligning impact to an impaction platewith this design.

FIG. 4 illustrates an alternative robotic device 400 embodiment to thedevices of FIG. 1-3 including a robotic control structure 405. Forexample, device 100 and/or device 300 may be mounted with robot controlstructure 405 and the co-axial impacts may be delivered mechanically bya robotic tool using pneumatic or electric energy.

FIG. 5 illustrates an alternative embodiment 500 to the devices of FIG.1-4 including a pressure sensor 505 to provide feedback duringinstallation. With respect to management of the force required for someof these tasks, it is noted that with current techniques (the use of themallet) the surgeon has no indication of how much force is beingimparted onto the implant and/or the implant site (e.g., the pelvis).Laboratory tests may be done to estimate what range of force should beutilized in certain age groups (as a rough guide) and then fashioning adevice 500, for example a modified sledgehammer 100 or cockup gun 300 toproduce just the right amount of force. Typically, the surgeon may useup to 2000 N to 3000 N of force to impact a cup into the acetabularcavity. Also, since some embodiments cannot deliver the force in anincremental fashion as described in association with the BMD3 device,device 500 includes a stopgap mechanism. Some embodiments of the BMD3device have already described the application of a sensor in the body ofthe impaction rod. Device 500 includes sensing system/assembly 505embedded in device 500, for example proximate rod 110 near distal end210, and used to provide valuable feedback information to the surgeon.Pressure sensor 505 can let the surgeon know when the pressures seems tohave maximized, whether used for the insertion of an acetabular cup, orany other implant including knee and shoulder implants and rods used tofix tibia and femur fractures. When pressure sensor 505 is not showingan advance or increase in pressure readings and has plateaued, thesurgeon may determine it is time to stop operation/impacting. Anindicator, for example an alarm can go off or a red signal can show whenmaximal peak forces are repeatedly achieved. As noted above, theincorporated patents describe a presence of a pressure sensor in aninstallation device, the presence of which was designed as part of asystem to characterize an installation pulse pattern communicated by apulse transfer assembly. The disclosure here relates to a pressuresensor provided not to characterize the installation pulse pattern butto provide an in situ feedback mechanism to the surgeon as to a statusof the installation, such as to reduce a risk of fracturing theinstallation site. Some embodiments may also employ this pressure sensorfor multiple purposes including characterization of an applied pulsepattern such as, for example, when the device includes automated controlof an impacting engine coupled to the hammer. Other embodiments of thisinvention may dispose the sensor or sensor reading system within ahandle or housing of the device rather than in the central rod or shaft.

FIG. 6 illustrates an alternative device 600 embodiment to the feedbacksystem of FIG. 5 including a sound sensor 605 to provide feedback forthe embodiments of FIG. 1-5. Surgeons frequently use a change in pitch(sound) to gauge whether an implant (e.g., the cup) has “bottomed out”(an evaluation of a “seatedness” of the implant) and device 600 includessound sensor 605 either attached or coupled to rod 110 or otherwisedisposed separately in the operating room. Sound sensor system/assembly605 may be used in lieu of, or in addition to, pressure sensorsystem/assembly 505 illustrated in FIG. 5.

FIG. 7-FIG. 10 illustrate prosthesis assembly embodiments including useof variations of the prosthesis installation embodiments of FIG. 1-FIG.6, such as may be used to reduce a risk of trunnionosis or for otheradvantage. FIG. 7 illustrates a modular prosthesis 700 and assembly tool705. Prosthesis 700 includes a head 710 and a trunnion taper 715 at anend of a stem 720 (e.g., a femoral stem for supporting a ball head tofit within an acetabular cup used in a total hip replacement procedure).During the procedure, the surgeon assembles prosthesis 700 by using tool705 which may include an impact rod 725 attached to a head coupler 730.The surgeon uses tool 705 to drive head 710 onto trunnion taper 715which conventionally includes a free mallet striking tool 705. Such aprocedure may be prone to the similar problems as installation of aprosthesis into an implant site, namely application of off-axistorqueing forces and an uncertainty of applied force and completion ofassembly.

It is believed that even a 0.1 degree mal-alignment on head 710 ontrunnion taper 715 may lead to progressive wear and metalosis.Variations of the embodiments of devices illustrated in FIG. 1-FIG. 6and its associated content may be developed to help resolve thisproblem. In the case of “non-torqueing axiality” of forces from anassembly device, a bore of the head may define an axis, the trunniontaper may define an axis, with the assembly device aligning these axesand then applying its forces in co-axial alignment with these co-axiallyaligned axes. Such an embodiment may reduce or eliminate anyforce-responsive rotations of the head with respect to the taper as thehead is seated into position by the assembly device.

FIG. 8 illustrates a femoral head 805, a variation of head 710illustrated in FIG. 7, to be assembled onto trunnion taper 715 that iscoupled to femoral stem 720. A center dot 810 may be placed on femoral(or humeral) head 805 to be impacted using tool 705.

FIG. 9 illustrates alignment of an installation device 900, a variationof any of devices 100-600, with femoral head 805 for properly alignedimpaction onto trunnion taper 715, such as an embodiment of FIG. 1-FIG.6 adapted for this application. Such adaptation may include, forexample, an axial channel 910 to view dot 810, and align forcetransference, prior to operation of hammer 105. Device 900 includes asledgehammer 915 and a cock-up spring to drive sledgehammer 915. A slot925 allows an operator to visualize a centering mark 930. Aspring-loaded structure 935 may be used to operate a device.

Dot 810 can be aligned with an impactor/device/gun. Once axialalignment, such as through the sight channel, has been confirmed, asledgehammer, a cockup gun, or other similar device can bang theimpactor onto femoral (humeral) head 805 to impact it on trunnion taper715. The co-axiality of the head and the device can be confirmedvisually (for example, through a hollow cylinder that comprises a centershaft of the device) or with a variety of electronic and laser methods.

FIG. 10 illustrates use of a modified vibratory system 1000, a variationof installation device 900 for assembly of the modular prosthesisillustrated in FIG. 7. Alternatively, to device 900, a variation of theBMD3 device can be used to insert the femoral and humeral heads 710 ontotrunnion taper 715. For example, a version of the BMD3 device wherefemoral head 710 is grasped by a “vibrating gun” and introducedmethodically and incrementally onto trunnion taper 715. Since there areno large forces being applied to the head/trunnion junction, there isessentially no possibility, or a reduced possibility, of head 710seating onto trunnion taper 715 in a misaligned fashion. It would bepossible to use the same technique of marking the center of head 710 andlining it up with trunnion taper 715 and device axially before operatingthe device.

FIG. 11-FIG. 12 illustrate an improvement to site 1100 preparation foran installation of a prosthesis 1105. FIG. 11 illustrates an environment1100 in which prosthesis 1105 is installed highlighting a problem withsite preparation for a prosthesis installation procedure having variabledensity bone (line thickness/separation distance reflecting variablebone density) of acetabulum 1110.

There is a secondary problem with the process of acetabular preparationand implantation that leads to cup mal-alignment. Currently, during theprocess of acetabular reaming, surgeons make several assumptions. Onecommon assumption is that the reamer is fully seated in a cavity andsurrounded on all sides by bone. Another common assumption is that thebone that is being reamed is uniform in density. Imagine a carpenterthat is preparing to cut a piece of wood with a saw. Now imagine thatparts of this piece of wood are embedded with cement and some parts ofthe piece of wood are hollow and filled with air. The carpenter's sawwill not produce a precise cut on this object. Some parts are easy tocut, and some parts are harder to cut. The saw blades skives and bendsin undesirable ways. A similar phenomenon happens in acetabularpreparation with a reamer and when performing the cuts for kneereplacement with a saw. With respect to the acetabulum, the side of thecavity that is incomplete (side of the reamer that is uncovered) willoffer less resistance to the reamer and therefor the reamerpreferentially reams towards the direction of the uncovering. Second,the reamer cuts the soft bone much more easily than the dense andsclerotic bone, so the reamer moves away from the sclerotic bone andmoves toward the soft bone. From a machining perspective, the reamingand preparation of the acetabulum may not be concentric or precise. Thismaybe a significant factor in the surgeon's inability to impact the cupin the desired location

FIG. 12 illustrates an alignment system 1200 for preparation andinstallation of a prosthesis to help address/minimize this effect. Afirst step that can be taken is to include directionality into theprocess of reaming at the outset, and not just at the last step duringimpaction. Current technique allows the surgeon to ream the cuphaphazardly moving the reamer handle in all directions, being ignorantlyunaware that he is actually creating a preference for the sinking pathof the acetabular implant. Ultimately the direction in which the surgeonreams may in fact be determining the position/path of the final implant.The surgeon then impacts the cup using the traditional A-frame or any ofthe currently used intra-operative measurement techniques such asnavigation or fluoroscopy. These methods provide information about theposition of the cup either as it is being implanted or after theimplantation has occurred. None of these techniques predetermine thecup's path or function to guide the cup in the correct path.

Proposed is a method and a technique to eliminate/reduce this problem.Before the surgeon begins to ream the acetabulum, the reamer handleshould be held, with an A-frame attached, in such a way to contemplatethe final position of the reamer and hence the implant, (e.g., hold thereamer in 40-degree abduction and 20-degree anteversion reaming isstarted). This step could also be accomplished with navigation orfluoroscopy. The surgeon could, for example, immediately mark thisposition on a screen or the wall in the operating room as describedbelow and as illustrated in FIG. 12. After the anticipated position ofthe reamer is marked, the surgeon can do whatever aspect of reaming thatneeds to be done. For example, the first reaming usually requiresmedialization in which the reamer is directed quite vertically to reamin to the pulvinar. Typically, three or four reamings are done. First,the acetabular cavity is medialized. The other reamings function to getto the subchondral bone in the periphery of the acetabulum. One solutionmay be that after each reaming, the reamer handle be held in the finalanticipated position of the implant. In some cases, it may be difficultto have an A-frame attached to every reamer and to estimate the sameposition of the reamer in the operating space accurately with theA-frame.

An alternative to that is also proposed to address this process. Forexample, at a proximal end of the reamer shaft handle will be placed afirst reference system 1205, for example a laser pointer. This laserpointer 1205 will project a spot 1210 either on a wall or on a screen1215, a known distance from the operating room table. That spot 1210 onwall 1215 (or on the screen) is then marked with another referencesystem 1220, for example a second independent laser pointer that sits ona steady stand in the operating room. Thereafter manipulating the shafthandle so that the first reference system has the desired relationship,example co-aligned, with the second reference system, the surgeon knowsthat the device attached to the handle has the desired orientation. So,when the first reamer is held in the anticipated and desired finalalignment of the implant (e.g., 40-degree abduction, 20-degreeanteversion for many preferred installation angles of an acetabularcup), the laser pointer at the proximal end of the reamer handleprojects a spot on the wall or screen. That spot is marked with thesecond stationary laser and held for the duration of the case. Allsubsequent reamings will therefore not require an A-frame to get a senseof the proper alignment and direction of the reamer. The surgeon assuresthat no matter how he moves the reamer handle in the process of reamingof the acetabulum, that the reaming finishes with the reamer handle(laser pointer) pointing to the spot on the wall/screen. In this manner,directionality is assured during the reaming process. In this way thesinking path of the actual implant is somewhat predetermined. And nomatter what final intra-operative monitoring technique is used (A-frame,C-Arm, Navigation) that the cup will likely seat/sink more closely tothe desired final position.

FIG. 13 illustrates modified surgical devices 1300 incorporatingvibratory energy as at least an aid to mechanical preparation. Alsoproposed herein is another concept to address a problem associated withnon-concentric reaming of the acetabulum caused by variable densities ofthe bone and the uncovering of the reamer. Imagine the same carpenterhas to cut through a construct that is made out of wood, air, andcement. The carpenter does not know anything about the variabledensities of this construct. There are two different saws available: onethat cuts effectively through wood only, and ineffectively through thecement. Also available is a second saw that cuts just as effectivelythrough cement as wood. Which of these saws would improve a chance ofproducing a more precise cut? Proposed is a mixing of ultrasonic energywith the standard oscillating saw and the standard reamer. In effect anyoscillating equipment used in orthopedics, including the saw, reamer,drill, and the like may be made more precise in its ability to cut andprepare bone with the addition of ultrasonic energy. This may feeldangerous and counterintuitive to some; however, the surgeon typicallyapplies a moderate amount of manual pressure to the saw and reamers,without being aware, which occasionally causes tremendous skiving,bending and eccentric reaming. An instrument that does not requires thesurgeon's manual force maybe significantly safer and as well as moreprecise and effective.

A further option includes disposition of a sensor in the shaft of theultrasonic reamers and saws so that the surgeon can ascertain when hardversus soft bone is being cut, adding a measure of safety by providing avisual numerical feedback as to the amount of pressure being utilized.This improvement (the ability to cut hard and soft bone with equalefficacy) will have tremendous implications in orthopedic surgery. Whenthe acetabular cavity is prepared more precisely, with significantlylower tolerances, especially when directionality is observed, theacetabular implant (cup) may more easily follow the intended sinkingpath.

Other applications of this concept could be very useful. Pressfit andingrowth fixation in total knee replacements in particular (as well asankle, shoulder and other joints to a lesser degree) are fraught withproblems, particularly that of inconsistent bony ingrowth and fixation.The fact that a surgeon is unable to obtain precise cuts on the bone maybe a significant factor in why the bone ingrowth technology has notgotten off the ground in joints other than the hip. The problem istypically blamed on the surgeon and his less than perfect hands. Theexperienced surgeon boasts that only he should be doing this operation(i.e.: non-cemented total knee replacement). This concept (a moreprecise saw that cuts hard and soft bone equally allowing lowertolerances) has huge potential in orthopedics, in that it can lead toelimination of the use of cement in orthopedic surgery altogether. Thiscan spark off the growth and use of bone ingrowth technology in allaspects of joint replacement surgery which can lead to tremendous timesaving in the operating room and better results for the patients.

Regarding ultrasonic assisted bone preparation in orthopedics, there isa problem with preparation of bone in joint replacement: theseprocedures are typically performed using conventional orthopedicequipment such as 1) saw, 2) broach, 3) reamer, and 4) burr.

FIG. 14-FIG. 17 illustrate a set of standard orthopedic bone preparationtools, FIG. 14 illustrates a perspective view of a powered bone saw1400, FIG. 15 illustrates a broach attachment 1500 for a poweredreciprocating bone preparation tool, FIG. 16 illustrates a hand-operatedreamer 1600, and FIG. 17 illustrates a set of bone preparation burrs1700. Conventionally, these tools include an operating motion with onedegree of freedom (e.g., saw 1400 has a blade that moves laterally,broach attachment 1500 reciprocates longitudinally, reamer 1600 andburrs of set of burrs 1700 each rotate about a longitudinal axis).

As noted below, these bone preparation tools may be enhanced by addingan additional vibratory motion component, preferably but not necessarilyrequired, that is “orthogonal” to the conventional cutting motion. Saw1400 includes a laterally reciprocating cutting blade that may beultrasonically enhanced by an additional ultrasonic vibratory motion inone of the other five degrees of motion (e.g., vertical, longitudinal,or vibratory rotations of the blade such as pitch, yaw, and/or roll).Similarly, each of the conventional tools has a primary mode of freedomof motion for the bone processing and an enhancement may be made byadding an additional vibratory motion in one or more other modes offreedom. Embodiments of the present invention may include an additionalvibratory motion, in the primary mode and/or the additional mode(s) thatmay be imperceptible visually (a very small amplitude and/or very fastabout or beyond 20,000 hertz).

During bone preparation, two types of bony surfaces are generallyencountered which include flat surfaces and contained surfaces. For theflat surfaces, seen in knee replacement, (end of the femur or the top ofthe tibia) saw 1400 is used to cut the bone. For the contained surfaces(such as the acetabulum and the proximal femur), as in hip replacementsurgery, broach attachment 1500 or reamer 1600 is used to prepare thebone.

A problem with all of these techniques is that the density of the boneis not uniform between patients and even within the same compartment orjoint of a single patient. The bone can be very soft or very hard andvary from region to region. With hard bone, saw 1400 may “skive” whichcauses an uneven cut surface and which minimizes that chance ofsuccessful “porous ingrowth”. This fact may be a principle reason thatcement is still used in knee replacement. For the contained bonecavities such as the acetabulum and proximal femur a “goldilocks”situation exists. During preparation, a surgeon may desire to know howwith confidence to prepare the bone to provide just the right amount ofcompressive (fit). Not too loose and not too tight. Too loose leads toloosening and potential infection of the prosthesis. Too tight leads toeither poor seating (which can lead to failure of fixation) or fracture(which leads to loss of press fit fixation and loosening).

Current art does not provide a reliable and consistent tool or methodfor the orthopedic surgeon to reliably prepare a (variable density bone)in order to obtain a “perfect” fit for the prosthesis, whether the boneis flat as in the tibia in knee replacement or contained as in theacetabulum in hip replacement.

For contained cavities such as the acetabulum, U.S. patent applicationSer. No. 15/234,782 filed 11 Aug. 2016 (all the content hereby expresslyincorporated by reference thereto in its entirety) described a basicestimation of the compressive forces involved in bone. This was named acompressive force and developed an FR curve where FR is related Fn. Us;where Fn represents the normal forces and Us represents the coefficientof static friction. Vis a vis Hooke's law the FR=K. x. Us. Where Krepresents the material properties of bone (the spring like quality ofbone) and x represents the amount of under-reaming of bone compared toan oversized prosthesis intended for press fit.

This current discussion mostly concerns itself with the variable “x”which represents the spring like quality of bone. In Hooke's law F=k. x;k is the spring's constant and x is amount of stretch placed on thespring. In orthopedic bone preparation k is represented by the materialproperties of bone and x is represented by the difference between thediameters of the prepared bone versus the prosthesis to be press fit.

As we have stated in the earlier papers, the surgeon and industry bothappear to have a poor understanding of the basic science of theprosthesis/bone cavity interaction. It is believed that x can be moretightly and precisely machined to give a better tuning of the bone,which is to accept an oversized prosthesis.

BMD3 bidirectional vibratory tool for preparation of bone, and inparticular the acetabular cavity: The use of an Acetabular Broach: a newidea. BMD3 bi-directional vibratory tool can be used for preparation ofbone (any cavity of bone that needs to be prepared for application of aprosthesis, but especially the acetabulum, as well as the proximalfemur, proximal tibia, proximal humerus, and any other long bone in thebody that receives a prosthesis). With regards to the acetabulum, unlikethe other bones discussed above, this structure has never before beenprepared with a broach, but rather always prepared with a hemispherical“cheese grater type” reamers that rotates in one direction (forward). Weare proposing that the acetabulum be prepared with a broach using one ofthe two degrees of freedom for oscillation

(1. Longitudinal and 2. rotational), utilizing a bidirectional BMDvibratory tool. The outer surface of this broach will very closelyresemble the rough surface of the prosthesis, with high coefficient ofstatic friction. We have seen this method in action in our experiments,particularly at higher frequencies of around 300 hertz, and believe thatthis method of acetabular preparation will provide a cut surface that ismuch more precise and conferring the ability to produce lowertolerances. This method may also allow preparation of acetabular cavityin “half” sizes. Currently the cavity is reamed in 1 mm intervals. Itmay be much easier to prepare the acetabulum with ½ mm interval broachesthan ½ mm reamers. Half size broaching may dramatically improve theability of the surgeon to cut and prepare the acetabular precisely andat lower tolerances.

For purposes of review we recall the equation FR=K. x. Us. Where x isrepresents the amount of under reaming and the shape of the cup beinginserted.

X is controlled by the amount of under or over reaming of theacetabulum. In the past when the surfaces of the cup were not as rough(lower coefficient of static friction, i.e. Zimmer Fiber Metal cup),surgeons used to under ream by 2 mm. Now most companies recommend underreaming by 1 mm, since the surfaces of most cups are much rougher withbetter porosity characteristics that allow better and quicker bonyingrowth. Sometimes when the surgeon has difficulty seating the cup,he/she reams line to line, and describes this action as “touching up therim”. This action however, many times, eliminates the compressivequality of the acetabulum by decreasing the value of x towards zero.This issue brings attention to the problem that we have described whichis that the surgeon does not have anything but a most basicunderstanding of the spring like qualities of bone. If he/she is canunderstand the basic science involved in this system, he can then usethe proper tools to appropriately fine tune the pelvis for a good pressfit fixation, without fear of under seating or fracture. There is a hugemarket need for better tools to prepare (fine tune) the acetabulum, forgood press fit fixation.

Current techniques utilize ‘cheese grater type’ hemispherical reamers toprepare the bed of the acetabulum. As discussed in our BMD4 paper thequality of acetabular bone can be drastically different between patientsand even within the same patient, particularly at different locationsaround the acetabular fossa. Some parts of the bone are soft, and someare hard. Current cheese grater hemispherical reamers come in 1 mmintervals. This creates two specific problems: 1. The current acetabularreamers in 1 mm intervals for preparation of the acetabular bone do notprovide the ability to precisely machine the acetabulum, and obtainlower tolerances, and therefore proper tuning of the pelvic bone. 2. Nomethod exists to cut hard and soft bone with the same level ofeffectiveness, i.e.: hard bone always pushes the reamers towards thesoft bone which ends up being chewed up more, and in that sense, aperfect hemisphere is not created with current cheese grater reamingtechniques. We therefore are proposing two distinct and separatesolutions which we believe can remedy this problem of poor-qualityacetabular preparation.

1. The creation of half reamers. The production and use of half reamersgive the surgeon the ability to ream up or down by half millimeters.Which gives him/her the ability to fine tune x more precisely, andtherefore FR more precisely. This basically gives the surgeon a betterset of tuning forks to obtain better tension for the acetabulum andutilize its viscoelastic properties to his/her advantage to obtain abetter press fit fixation.

2. Ultrasonic assisted reaming or broaching: Lastly, we believe thatthere is some room for creating a better cutting tool by addingultrasonic energy to either the acetabular broach described above, orthe acetabular half reamers described above to create an ultrasonicassisted reaming or broaching of the acetabulum for obtaining a moreprecise cut and at a lower tolerance. We believe this is a new and novelidea that can be considered for preparation of the acetabulum forobtaining better tension of the pelvis for application of an acetabularprosthesis.

The following further elaborates upon ultrasonic assisted preparing,milling, burring, sawing, broaching, reaming, and the like in order toobtain a more precise and efficient process of bone preparation in jointreplacement surgery.

Another important advance in orthopedics is the use of robotics in theoperating room. Sensors and computer-controlled electromechanicaldevices are integrated into a robot with a haptic sense, where roboticmanipulators now have a complete spatial sense of the patient's bone inthe operating room, sometimes to within a half millimeter of accuracy.

Currently robots such as the Stryker Mako robot use a standard rotatingburr, reamer or a standard saw to prepare the bone for application of aknee or hip prosthesis. The term “robot” has a special meaning in thecontext of preparation of live bone in a living patient. Currently it isimpermissible to automate any cutting of the live bone. Robot in thissense operates as a realtime constraint that provides haptic feedback tothe surgeon during use when certain movements of the processing tool areoutside predetermined limits.

An advantage of the robot is that it is helps in processing bone towithin less than half a millimeter. This means that the surgeon cannoteasily push the burr, reamer or saw out of the allowed haptic plane. Ina sense, with the robot, the cutting tool is in safer hands. Thesestandard tools (burr, saw, reamer) provide no particular advantage forthe robotic system, that is, the conventional robotic system usesconventional tools with the constraint haptic system. A disadvantage ofthe robot is that the process of cutting bone with a burr, saw andreamers are very inefficient (slow) especially in hard sclerotic bone.The robot is also very a bulky piece of equipment that adds time to theoperation. Mako or other robotic knee surgeries have been somewhatadopted in the uni-compartmental knee replacement procedures (less than10% of surgeons) and is currently being investigated for use in totalknee replacement (Not yet in general markets). The use of the Mako robotin hip replacement however, has shown a very poor adoption rate; lessthan 0.01% of surgeons have used the Mako robot for hip replacement.Some of the weakness of this robotic procedure is in the process of 1.bone preparation and 2. the actual insertion of the prosthesis intobone.

Earlier tools have addressed tools for installing an acetabular cup intothe bony cavity with either “vibratory-BMD3” technique or “discreteimpact-BMD4” technique. These solutions are believed to largelyeliminate the problems associated with insertion of the prosthesis,providing the ability not only to insert but also to position theprosthesis in proper alignment. Other tools have dealt with manipulatingthe value of Us, coefficient of static friction, during a process ofinsertion.

An embodiment of the present invention may include a better job ofpreparation of bone. In effect, some embodiments provide a tool orprocess that more precisely manipulates the value of x in the formula:FR=K. x. Us. A goal of some embodiments of the present invention is toobtain lower (tighter tolerances) and do it more quickly, with differenttools and methods such as disclosed herein.

An embodiment of the present invention may include bone preparationusing robotic surgery through use of haptic control and management toprovide an unprecedented level of safety and accuracy coupled withmodified equipment that more efficiently prepares in-patient bone whileoffering novel solutions for bone preparation. In some of theseimplementations the robotic haptic feedback may be exploited by additionand utilization of a more powerful and efficient bone cuttingtool/method never before used or contemplated in orthopedics as it wouldhave been too easy to mis-process a bone portion.

Ultrasonic motion may be added to traditional bone processing tools(e.g., to the tools of FIG. 14-FIG. 17) to offer effectivenon-traditional bone processing tools. This addition of ultrasonicenergy to standard cutting, milling, reaming, burring and broachingtechniques can be used to provide (methods and tools) in orthopedicsurgery to remove bone more effectively with a (higher material removalrate) MMR and with significantly less force, and therefore moreefficiency.

Specifically, in hip replacement surgery the traditional reamer, broachor burr can each be equipped with an ultrasonic transducer to provide anadditional ultrasonic vibratory motion (e.g., longitudinal axialultrasonic vibration). These new cutting methods can then beincorporated within, or in association with, a robot that only allowsoperation of the tool within safe haptic zones. This ultrasonic roboticcutting tool is therefore more powerful, fast and precise. It would cuthard and soft bone with equal efficiency. Additionally, the roboticoperation of an ultrasonic assisted cutting tool is safe, in that therobot does not allow operation of the tool outside of the haptic safeplanes.

For example, a Mako robot may be equipped with a rotatory ultrasonicbone preparation tool, operating a bone processing tool (such as singlemetal-bonded diamond abrasive burr) that is ultrasonically vibrated, forexample in the axial direction while the burr is rotated about thisaxis. This tool can prepare both the proximal femur and acetabulumquickly with extreme precise. This tool and method therefore do awaywith the standard manual broaching techniques used for femoralpreparation and the standard reaming techniques used for acetabularpreparation.

An implementation of this system of a constrained ultrasonic vibrationof a bone processing tool such as a rotating burr enables athree-dimensional bone-sculpting tool or a smart tool robot. Thesculpting tool and smart tool robot may allow a surgeon to accurately,quickly, and safely provide non-planar contours when cutting bones asfurther described below while also potentially replacing all theconventional preparation tools of FIG. 14-FIG. 17.

The addition of the ultrasonic bone preparation tool to a robot makesthe system a truly efficient and precise tool. The surgeon can sculptthe surfaces of the bone, for example a femur, tibia or an acetabulumand the like, and in some implementations any tissue may be sculptedwith the sculpting tool, with high degree of accuracy and speed.

With current tools, it would take too much time to perform such bonepreparation with a burr, making the operation extremely slow and addingrisk to the patient and is therefore not performed. Some implementationsinclude an addition of an improved bone processing tool to anyhaptically constrained system will make the preparation of bone forjoint replacement easy, fast and efficient, ultimately delivering on thepromise of a better, faster and more precise operation.

With respect to knee and shoulder replacement, some of the bone surfacesare flat which have led to prosthetic designs that have a flatundersurface, and the decision to prepare these bones with a saw. Oneconcept is to add ultrasonic axial vibrations to the saw for a moreeffective cut.

Ultrasonic enhancement may be added to all current bone removaltechniques in orthopedics, including the burr, saw, reamer, and thebroach, making all of these bone preparation tools more effective.

In some instances, use of the same burr described above (e.g., arotating tool with metal-bonded diamond abrasives that is ultrasonicallyvibrated in the axial direction) to prepare surfaces of the tibia, femurand the glenoid in the shoulder for mating to an implant surface. Oneimportant benefit of use of such a burr is that the surgeon and thesmart tool robot can now very quickly and effectively machine thesemating surfaces any way desired, potentially introducing waves andcontours that can match the undersurface of the prosthesis (which itselfhas been created with waves and contours for additional stability.Portions of the tibia and the glenoid in the shoulder are flat bonesthat do not have inherent stability. These bones are prepared in such away to accept a prosthesis with a flat surface. With the advent ofhigh-power 3D bone sculpting, 3D printing, and smart tool hapticconstraint, the sculpting/smart tool system may create prostheses thathave waves and contours on their bottom surface to enhance stabilitywhen mated. For example, a bone surface may be 3D sculpted/contoured anda prosthesis produced to match the profile, or a preformed contouredprosthesis may be provided with a non-flat profile and the mating bonesurface may be sculpted/contoured to match the preformed non-flatprosthesis mating surface, particularly for the “flat ended” bone andthe associated prostheses. These contouring profiles for bone andimplant mating surfaces are not limited to “flat ended” bones and mayhave benefit in other implants or bone mating surface.

These changes can enhance the initial fixation of the prosthesis to boneby creating contact surface areas which are more resistant to shearforces. This may provide a specific advantage for the tibial componentin knee and the glenoid component in shoulder replacement surgery. Theseprostheses generally have flat undersurfaces and are less inherentlystable. They can be made significantly more stable with the suggestedchanges in the method of bone preparation and prosthesis fabrication.

FIG. 18 illustrates a side view of a first set of components 1800 for aconventional bone preparation process and FIG. 19 illustrates a sideview of a second set of components 1900 for a three-dimensional bonesculpting process that may be enabled by some embodiments of the presentinvention.

Components 1800 include a bone B (e.g., a tibia) having a flat end 1805.Flat end 1805 is typically removed by a conventional version of saw1400, to allow an implant 1810 to be installed. In the conventionalprocess, bone B is prepared having a flat/planar bone mating surface1815 which matches a flat/planar implant mating surface 1820 of implant1810. As noted, the pair of mated surfaces may exhibit instability,especially with lateral shear loading.

Components of 1900 include bone B that has been prepared differently byremoving flat end 1805 using an orthopedic sculpting system as describedherein. The sculpting system enables use of an implant 1905 thatincludes a contoured (non-flat/planar) implant mating surface 1910. Abone mating surface 1915 produced by the orthopedic sculpting system iscontoured to match/complement implant mating surface 1910. Components1900 may include a preformed implant 1905 and surface 1915 is sculptedto match/complement for bonding or surface 1915 is sculpted and surface1910 is thereafter formed to match/complement surface 1915. Anadditive/subtractive manufacturing process may be used to make surface1910 and/or implant 1905. For example, implant 1905 may include twoportions—a premade head portion and a later-formed body portion that maybe contoured or manufactured as needed to produce surface 1910, with thehead portion and body portion joined together to produce implant 1905

Bone ingrowth technology has not enjoyed that same success in shoulderand knee replacement surgery as it has done in hip replacement surgery.One reason that this may be true is because current methods do not allowprecise and uniform preparation of bone due to variable density of bone,and especially on the flat surfaces. The ultrasonic assisted bonepreparation (example, the orthopedic sculpting system or smart toolrobot) discussed herein has a potential to solve this problem ofinconsistent bone preparation. The use of the above bone preparationmethod/tools instead of the standard techniques may represent adisruptive technology. The ability to quickly machine bone, and to do itin an extremely precise and safe manner may eliminate the need for bonecement in joint replacement surgery. This fact can cause an explosion inthe use of porous ingrowth prosthesis/technology in orthopedics jointreplacement surgery.

FIG. 20 illustrates a plan diagram of a smart tool robot 2000 which mayinclude a type of three-dimensional bone sculpting tool. Robot 2000includes a controller 2005 coupled to a linkage 2010 which is coupled toa high-efficiency bone preparation tool 2015, with tool 2015 including abone processing implement 2020. Controller 2005 includes systems andmethods for establishing and monitoring a three-dimensional spatiallocation for implement 2020. Controller 2005 further includes governancesystems for linkage 2010. Collectively controller 2005 and linkage 2010may be a type of constraint, other systems and methods for another typeof constraint and providing feedback may be included in some embodimentsof the present invention.

Linkage 2010, illustrated as including a mechanically limitedarticulating arm, is coupled to both controller 2005 and tool 2015. Insome cases when processing a particular in-patient bone, controller 2005may predefine a set of bone regions of the in-patient bone for aprocessing (e.g., a cutting, a removing, a reaming, a sawing, abroaching, a burring, and the like). Controller 2005 may monitor arelative location of implement 2020 relative to a particular portion ofthe in-patient bone to be processed and compare that particular portionwith the predefined regions. Those predefined regions may include afirst subset of regions to be processed by implement 2020 and in somecases also include (or alternatively substitute for the first subset) asecond subset of regions not to be processed by implement 2020.Controller 2005 provides a realtime feedback to the user regarding anappropriateness or desirability of processing each the particularportion of bone at the location of implement 2020.

In some cases, the realtime feedback may include a realtime hapticsignal imparted from controller 2005 through linkage 2010 to tool 2015.That haptic signal may be of sufficient strength to significantlyrestrict an ability of an operator to casually move implement 2020 to aregion of the in-patient bone that is not to be processed, and somecases may essentially prevent or inhibit the locating of implement 2020to those regions of the in-patient that are not to be processed.

Other feedback signals may be included in addition, or in lieu of, thehaptic system. Audio feedback may in some cases be sufficient to providefeedback to an operator.

Tool 2015 may be an embodiment of an ultrasonically enhanced bonepreparation tool which operates implement 2020. Tool 2015 includes amotive system that operates implement 2020 with a bone processingmotion. The bone processing motion includes a primary motion having aprimary freedom of motion (e.g., for a burr as illustrated, the primarymotion may include a rotation about a longitudinal axis, this primarymotion having a freedom of motion that includes the rotation about thelongitudinal axis). The bone processing motion includes a secondarymotion having a secondary freedom of motion, the secondary freedom ofmotion different from the first freedom of motion. The secondary motionincludes an ultrasonic vibratory motion that enhances thebone-preparation of implement 2020 than would be the case of the primarymotion alone.

Different implements and tools may include varying primary and secondarymotions, there generally being six freedom of motion possibilities forthe primary or secondary motions: x, y, and z translations and rotationsabout any of the x, y, and z axes. Typically, the primary motion willinclude a repetitive (and sometimes reciprocating) component.

An operator grips tool 2015 and manipulates it by hand. Controller 2005automatically monitors these manipulations to establish a relativelocation of implement 2020 with respect to a particular portion of anin-patient bone. Comparison of the relative location topredetermined/premapped regions of the in-patient bone that identifyprocessable/non-processable regions results in controller 2020 is usedto provide appropriate realtime feedback signals to the operator foreach particular portion of bone.

Oscillating (sometimes referred to as sagittal) saws are frequently usedin sectioning bones during total knee and hip arthroplasty. Standardoscillating saws utilize an electric motor to generate rotatory motionwhich is coupled to an eccentric mechanism the produces oscillatory sideto side motion (i.e., a sagittal motion) which operate at frequencies ofabout 10,000 to 20,000 cycles per minute (cpm), at a relatively smallangle of 3 to 6 degrees within a plane defined by the flat blade.

High oscillations over a short stroke length of 3 mm to 7 mm producessignificant friction and heat generation potentially causing necrosis ofosteocytes and bone cells, which may adversely affect bone ingrowth andosteointegration into any porous surfaces of implants installed insectioned bone.

Superimposition of ultrasonic/near ultrasonic oscillations (withfrequencies in the order of 20 kHz to 50 kHz and amplitudes of between15 μm to 150 μm) on top of the sagittal motion or sagittal-like motionof an improved sagittal saw are included as embodiments andimplementations of the present invention. For example, an addition ofaxial ultrasonic oscillations to the sagittal saw motion may produce asmoother cut with lower temperatures that is associated with decreasedcutting force, increased cutting efficiency and material removal rate.It is also the case that addition of such an axial ultrasonic energy tothe action of the sagittal saw may produce a smoother cut with smallerchip size and less subsurface damage to the bone being sectioned. Thiswould have significant positive ramifications by minimizing heatgeneration, decreasing a risk cell death from heat, and decreasing apotential loss of vascularity of bone, which may lead to enhancedhealing of implants to bone sectioned with the improved sagittal saw.

Generally, a housing includes a set of driver components, including aprimary motion driver and one or more secondary motion drivers, coupledto an adapter, the adapter attached/coupled to the sagittal saw blade.The conventional sagittal saw blade is typically a rectilineararrangement including a long and thin structure configured formechanical removal (e.g., chipping) of bone. A longitudinal axis extendsalong a longest distance (length) dimension, a lateral axis,perpendicular to the longitudinal axis, extends along an intermediatedistance (width) dimension, and a yaw axis, perpendicular the otheraxes, extends along a shortest distance (thickness) dimension. Thesagittal saw provides a primary sagittal motion for the sagittal bladein a sagittal plane containing the longitudinal and lateral axes. Thisprimary sagittal motion is configured to section a bone upon applicationof the sagittal blade to the bone. Blade motion includes displacementand/or rotation in any of these three axes (e.g., the 3-6-degreerotation about the yaw axis within the sagittal plane defined by thelongitudinal and lateral axes). Some profiles may include puredisplacement along one or more axes, pure rotation about one or moreaxes, or some combination.

The ultrasonic component may be produced by piezoelectric structures,such as crystals, ceramics, transducers, motors, spindles, or ceramicswhich produce a mechanical strain with applied electrical field; or morecomplex piezoelectric producing structures such as piezoelectric stacks,piezoelectric actuators, piezoelectric ultrasonic spindles, all of whichproduce higher efficiency (amplitude and frequency) ultrasonicvibrations.

Superimposed on this primary sagittal motion is a secondary motion thatincludes a set of driven vibrations configured to enhance the sectioningability of the primary sagittal motion, the secondary motion may beconstrained within the sagittal plane as well, but may include somemotion component in the pitch axis as well. Disclosed herein areembodiments wherein the set of driven vibrations includes ultrasonic ornear-ultrasonic motions with an amplitude at least 12 kHz to 17 kHz atthe lower subsonic limit, and preferably at least 20 kHz for ultrasonicimplementations and more preferably at least 20 kHz to 40 kHz.

The sagittal motions are generated by driver components that may bedisposed in a series arrangement, in a parallel arrangement, or in ahybrid arrangement including some series and parallel cooperatingarrangement.

Multiple specific design embodiments of the improved sagittal saw aredescribed herein.

In one specific design embodiment, a saw having a primary eclecticrotatory motor is coupled with an eccentric mechanism that providesrapid oscillations at high frequency in the order of 10,000 to 20,000oscillations per minute cpm in a relatively small angle that moves thesagittal blade about a center of oscillation where coupled to a drivemechanism that includes the eccentric mechanism. The eccentric mechanismis then attached to an elongated horn having a first broad horn end anda second narrow horn end wherein the second horn end is attached to theoperative tip, and the first horn end extends through the axial bore ofa piezoelectric transducer element and is attached to the transducerelement, wherein a broad portion includes a first nodal point of theelongated horn and the narrow portion includes a second nodal point ofthe elongated horn. The elongated horn is coupled to the operative tip(e.g., sagittal saw blade). There are many conventional means to capturethe sagittal saw blade, including but not limited to male female threadsor a clamping jaw. Ultrasonic sagittal saw blades are designed forultrasonic machines and should be made of high strength material such astitanium, cobalt chrome, or stainless steel. Standard sagittal sawblades can be used with the addition of an ultrasonic adaptor thatprovides proper tuning of the blade.

A primary motor may or may not include desynchronization or decouplingelements between various drive components, such as the primary engineand the eccentric mechanism to allow a for desynchronization ofoscillations from the primary motive engine to the eccentric mechanism.

A second embodiment of the ultrasonic sagittal saw attaches theeccentric mechanism distal to an ultrasonic transducer and horn. Thesecond embodiment has a primary motor coupled to a rotating (plate/arm,collectively referred to as a cover) which is coupled to a proximalnodal point of the elongated horn through elastic elements that minimizecontact area, which minimize loss of ultrasonic energy.

The horn is attached to a piezoelectric transducer/actuator through theaxial bore of the piezoelectric transducer element (generally ceramicpiezoelectric transducer, but not limited to ceramic-many differentkinds available including piezo and non-piezo technologies forproduction/generation of desired driven vibratory motion as describedherein).

The saw has a housing that is attached to the primary motor proximallyand attached to the distal nodal point of the elongated horn throughelastic elements that minimize contact area and minimize loss ofultrasonic energy.

The distal aspect of the horn is attached to an eccentric mechanism thatconverts the now combined (subsonic rotatory and ultrasonic axialmotion) into rapid side to side oscillations that will contain axialultrasonic oscillations with frequencies of up to 20 kHz to 50 kHz andamplitudes of between 15 μm to 150 μm. The eccentric mechanism mayproduce a third nodal point for the acoustic waves. The eccentricmechanism attaches either to a specialty saw blade made for ultrasonicoperation or to a specialized ultrasonic adaptor that allows use ofstandard blades. The dimensions of the horn/adaptor/blade or(horn/blade) complex are tuned for desired frequency and displacement atthe tip of the cutting implement (saw). A cooling system provides coolair/liquid through a tubing system and subsequently through special slotin the blade to the blade tip-bone interface to counteract heatgeneration.

Driver components may include a wide range of motors and actuators.There are generic mechanical templates for producing vibratory forcesand motions as described herein. One mechanical template may convert arotary motion of an engine (e.g., a rotary motor) into a motion of anadapter, such as one coupled to a sagittal saw blade. Another mechanicaltemplate for a mechanical device may convert a pneumatic engine intomotion of an adapter. Still another mechanical template may convertmotion of an actuator (e.g., a piezo electric actuator) into a motion ofan adapter. The systems are variations on the theme of conversion of onemotion of a motive component into motion of the adapter. An engine thatproduces the vibration or motivation that results in driving the bonepreparation implement into bone for sectioning could be of any varietyincluding a brush DC motor, stepper motor, piezo (ultrasonic) motorproducing sub sonic or ultrasonic motion, single and stackedpiezoelectric materials and crystals, ultrasonic spindles, brushless DCmotor, linear motor (actuators) or pneumatic motor, or combinationsthereof, for example, and which may or may not require an intermediarymotivation processor (e.g., a linear motion converter) to producevibrations applied to the sagittal saw blade directly or indirectlythrough an adapter coupling, from motivations from the engine through apulse transfer mechanism which may include the adapter. These motors canall produce a pulsation or set of motivations that can be transferredthrough a “pulse transfer system” to the entire adapter/implement/blade,the profile of the force applied to the adapter/implement/blade mayinclude or consist of a set of intentional driven vibration componentsin any of one to six degrees of freedom and combinations thereof. Insome implementations, the entire blade moves in unison in one or moresix degrees of freedom, and in other implementations different parts ofthe entire blade may move at different velocities in one or more degreesof freedom.

FIG. 21 illustrates a vibratory sagittal saw 2100 that includes asagittal saw blade 2105 operated by a vibratory drive 2110 through anadapter 2115 securing blade 2105 to drive 2110. Blade 2105, arectilinear structure having an elongate thin arrangement with a set ofdistance dimensions, in decreasing magnitude, of a length, a width, anda thickness. Blade 2105 defines a sagittal plane containing the lengthand width. Extending in the length dimension is a longitudinal axis 2115and extending in the width dimension is a lateral axis 2125, axis 2125perpendicular to axis 2120. Saw 2100 includes a controller 2130 coupledto drive 2110 to initiate, configure, and/or control drive 2110 toproduce the desired driven vibratory motion through use of controlsignals provided to driver 2110 from controller 2130. In someimplementations, controller 2130 controls the vibration elements so thatdesired vibration amplitude in the desired freedom(s) of motion isappropriately maintained during bone processing. This may include, butis not limited to, increasing power while allowing a vibrationfrequency/oscillation to decrease to maintain/sustain the desiredvibratory amplitude within the predetermined thresholds.

Drive 2110 imparts a desired drive profile to blade 2105 through adapter2115, the drive profile predominately, if not exclusively, is containedwithin the sagittal plane. The drive profile including a primary drivemotion and a secondary drive motion, operates blade 2105 to remove bonewhen blade 2105 is applied to a portion of bone. This bone removal mayinclude mechanical removal, cavitation/emulsification removal, or both,among other bone removal methodologies.

The primary drive motion or the secondary drive motion (or both) mayinclude subsonic or ultrasonic drive components contributing to a drivenvibratory motion of blade 2105 during bone removal operations. Drivenvibrations are in contrast to passive or secondary effects of a drivensystem which may be simply dampened by contact of blade 2105 to bone. Asdiscussed herein, an amplitude/effectiveness of the vibratory motion(s)is/are not functionally degraded during the active sectioning of thebone with application of the implement against the bone.

These motors can all produce a pulsation or set of motivations that canbe transferred through a “pulse transfer system” to the entire implantor bone preparation implement, the profile of the force applied to theentire implant/implement may include or consist of a set of intentionaldriven vibration components in any of one to six degrees of freedom andcombinations thereof.

An embodiment of the present invention may provide a blade profile thatincludes a blade oscillation at a rate of 10,000 to 40,000 oscillationsper minute at an angle of 4-6 degrees and have an axial ultrasonicoscillation of 20 kHz to 40 kHz with amplitudes of 10 μm to 150 Mmdirectly superimposed on it. For series coupled driver components thatare commutative, an order of generation of primary or secondary motionsproduces a same superimposed motion of the adapter (and of the blade).For commutative drivers, order does not matter. In some systems, it maybe that order variations produce different superimposed motions(non-commutative drivers).

The driver, and driver components, may be configured with various rotarymotive elements that include a conversion of these motive elements intothe desired primary and secondary motions in the one or more freedoms ofmotion (e.g., X-axis, Y-axis, and/or Z-axis displacement(s) and/orrotation(s). The driver, and driver components, may also be configuredwith various linear motive elements that may directly produce thesedesired primary and secondary motions. In other cases, the variouslinear motive elements may indirectly produce these desired primary andsecondary motions, such as through amplitude boosting or amplification,or other motion conversions.

For example, one primary driver component may include a linear motordriving a primary motion of the adapter (and thus the entire cuttingimplement coupled to the adapter) and another driver component mayinclude some other motor (rotary, linear, or other) producing one ormore motion elements of the secondary motion. This arrangement could bereversed as to primary and secondary motion drivers, among other driver,driver component, and motion variations.

Applying and superimposing a desired sub-component (e.g., ultrasonic) ofthe final motion profile, with other motions (e.g., primary motion) fromoff-implement drivers to the bone preparation implement through theadapter, for example by moving the adapter, enables a greater range ofmotion than may be possible with one or more driver components disposedon the blade. In some applications, the bone-processing implement isrequired to be disposable after each procedure. Incorporating drivercomponents into a disposable bone-processing implement increases thecosts of using such an implement. Decreased and less effective driveroptions and increased costs associated with disposing of more expensiveblades likely decrease adoption of on-blade driver solutions. Anembodiment of the present invention does not include any drivercomponents on the preparation implement and all driven motions (primaryand secondary for example) are provided from off the blade through theadapter that releasably engages and secures the bone preparationimplement during application of the motions to the implement through theadapter. This adapter is separate and distinct from the cuttingimplement and may, in some implements, help to tune the cuttingimplement for certain motions (e.g., ultrasonic motion).

FIG. 22 illustrates an embodiment of a vibratory sagittal saw 2200 ofthe type illustrated in FIG. 21 including a set of series-coupled drivercomponents (a first driver component 2205 and a second driver component2210). An output of component 2205 is coupled to component 2210 andcombined and applied to adapter 2215 to produce the desired driveprofile. One of the components may produce the primary drive motion andthe other component may produce the secondary drive motion. In otherembodiments, the primary and secondary motions may result collectivelyfrom a combination the components. Some embodiments may include morethan two series-coupled driver components performing as describedherein.

FIG. 23 illustrates an embodiment of a vibratory sagittal saw 2300 ofthe type illustrated in FIG. 21 including a set of parallel-coupleddriver components (a first driver component 2305 and a second drivercomponent 2310). Outputs of component 2305 and component 2310 are bothapplied to adapter 2315 to produce the desired drive profile. One of thecomponents may produce the primary drive motion and the other componentmay produce the secondary drive motion. In other embodiments, theprimary and secondary motions may result collectively from a combinationthe components. Some embodiments may include more than twoparallel-coupled driver components performing as described herein.

FIG. 24 illustrates an embodiment of a vibratory sagittal saw 2400 ofthe type illustrated in FIG. 21 including a set of hybrid-coupled drivercomponents (a first driver component 2405 and a second driver component2410). Outputs of component 2405 and component 2410 are both applied toadapter 2415 to produce the desired drive profile. One of the componentsmay produce the primary drive motion and the other component may producethe secondary drive motion. In other embodiments, the primary andsecondary motions may result collectively from a combination thecomponents. Some embodiments may include more than two hybrid-coupleddriver components performing as described herein.

FIG. 25-FIG. 27 illustrate exemplary implementations of the set ofvibratory saw templates illustrated in FIG. 21-FIG. 24. FIG. 25illustrates a generalized plan diagram for a first embodiment of anultrasonically assisted sagittal saw 2500 driving a bone preparationimplement (saw blade 2105). Saw 2500 includes a primary driver component2505 (e.g., a rotary motor) coupled to a drive converter 2510, in thiscase an eccentric element, converting rotary motion of component 2505into a primary cutting motion. Driver component 2505 is one driver of aset of series-coupled driver components.

Saw 2500 further includes a second driver component in the set ofseries-coupled driver components. This second driver component producesdriven vibratory motion superimposed on the primary cutting motion for avibratory motion profile to be applied to blade 2105. Second drivercomponent may include a vibration driver 2515 which produces an initialdriven vibratory motion, such as subsonic, near ultrasonic, and/orsupersonic/ultrasonic motion. For ultrasonic initial driven vibratorymotion, vibration driver 2515 may include piezo generators as describedherein (e.g., crystals, ceramics, transducers, actuators, motors,spindles, and the like) producing an initial vibratory motion. Seconddriver component may further include a motion booster 2520 and/or motionamplifier 2525 to increase an amplitude of the initial vibratory motionproducing an amplified vibratory motion as the driven vibratory motion.Motion amplifier 2525 for ultrasonic motion may include an ultrasonichorn that tunes the vibratory ultrasonic motion for the operationalfrequency and blade 2105.

An adapter 2530, coupled to blade 2105, applies the vibratory profilegenerated from the series-coupled driver components to the entire blade2105. Adapter 2530, and one or more elements of the series-coupleddriver components, may be used to tune ultrasonic frequencies/motion.

FIG. 26 illustrates a generalized plan diagram for a second embodimentof an ultrasonically assisted sagittal saw 2600. Saw 2600 includes avariation of saw 2500 that includes a decoupler/desynchronizer 2605disposed within the series-coupled driver components. In some instances,it may be desirable to convert randomly one motion into another motionand decoupler/desynchronizer 2605 may provide that randomization.

FIG. 27 illustrates a generalized plan diagram for a third embodiment ofan ultrasonically assisted sagittal saw 2700 using hybrid coupled drivertemplate from FIG. 25. Saw 2700 includes a primary motor 2705 coupled toa rotatable plate 2710 coupled in turn to a rotatable arm 2715. Primarymotor 2705 produces a motor motion (e.g., rotation). Within rotatablearm 2715 is a secondary driver component producing vibratory motion thatis superimposed on the motor motion. Secondary driver component mayinclude a vibration driver 2720 which produces an initial drivenvibratory motion, such as subsonic, near ultrasonic, and/orsupersonic/ultrasonic motion. For ultrasonic initial driven vibratorymotion, vibration driver 2720 may include piezo generators as describedherein (e.g., crystals, ceramics, transducers, actuators, motors,spindles, and the like) producing an initial vibratory motion. Seconddriver component may further include a motion booster 2725 and/or motionamplifier 2730 to increase an amplitude of the initial vibratory motionproducing an amplified vibratory motion as the driven vibratory motion.Motion amplifier 2730 for ultrasonic motion may include an ultrasonichorn that tunes the vibratory ultrasonic motion for the operationalfrequency and a blade 2735.

An adapter 2740 couples the drive to blade 2735 so that motion producedfrom the drive is applied to blade 2735. The drive may include aneccentric element 2745 to further modify a rotation motion in the driveto a desired blade profile motion applied to blade 2735.

In some embodiments saw 2700 may include an optional cooling systemincluding a fluid reservoir 2750 and a fluid conduit 2755 directingcontents of reservoir 2750 to a fluid channel 2760 disposed within blade2735. The fluid in reservoir may be a liquid or gas to help reduce anyheat generated during operation of saw 2700 during bone preparation.

FIG. 28 illustrates a perspective view of a sagittal saw blade 2735 thatmay be used in a vibratory/ultrasonically assisted sagittal saw such asillustrated in FIG. 13, FIG. 14, and FIG. 21-FIG. 27, particularly FIG.27. Blade 2735 includes a channel 2805 for receiving a fluid, such asmay be used for cooling blade 2735 during operation. The fluid channeldirects the fluid as desired, such as to a portion of the blade (e.g., acutting edge of a saw blade or other region where temperature may rise).In some embodiments, the fluid may be directed to the in-patient boneduring processing by the bone processing implement, such as for coolingthe bone, lubrication, or other use.

In some embodiments, a bone preparation tool may include a temperaturesensor for measuring a temperature. The temperature may be of the bonepreparation implement or of the in-patient bone being processed by thetool. The temperature may be measured directly or indirectly, by acontact sensor or remote temperature sensing.

Bone can be classified by its level of compactness (density). Also, theosteons in bone may have different configurations as seen in wood.Certain bones, based upon bone density among other factors, may benefitfrom different bone preparation processes, cutting tools, and cuttingforces having density-tuned variations of vibration superimposed on aprimary bone preparation motion of a bone preparation implement.

An embodiment of the present invention may include orthopedic cuttingimplements (e.g., saws, burrs, reamers, broaches and reamers) thatinclude driven vibrations that may be tuned (e.g., based on bonedensity) with various single or combination vibratory motion in thesagittal, coronal, and axial planes.

For example, certain bones may be more easily prepared (e.g., cut) withaddition of a single plane ultrasonic vibration. Some of the morecompact bones may be more efficiently cut with addition of a combinationof ultrasonic plane vibrations.

For example, nine different combinations of ultrasonic tuning may beadded to an orthopedic bone preparation implement to increasepreparation efficiency, while reducing preparation force, and reducingrisks of heat generation, subsurface damage, and delamination, whilepotentially preserving osteocyte health and vascularity producing asmoother finish with smaller cutting chips.

A particular set of tuned vibratory motions, subsonic, near ultrasonic,and ultrasonic for example, or a particular implement, bone, and bonepreparation profile (e.g., a resection when cutting bone, a reaming whenpreparing a cavity for an acetabular cup, a broaching for a long bonechannel. These sets of tuned vibratory motions are likened to a“symphony” of secondary motions/frequencies that may be specialized andsuperimposed on a primary bone preparation motion/implement. Thespecifics of each symphony may be based on many factors, including acompactness (density) of bone and a configuration and alignment ofosteons at the bone preparation site.

Primary vibratory addition may be axial, coronal, and/or sagittal in theorder 15 to 150 μm. Secondary vibratory superposition may be in theorder of 4 to 20 μm in one or more of these planes. One or moresecondary vibrations may be added based on the compactness of bone orthe positioning and alignment of these osteons. The same tool mayinclude a controller that adjusts these magnitudes in the various planesto allow the tool to be used with different bone density configurationsor bone preparation actions.

As used herein, this bone-tuning may sometimes be referred to herein asbandwidth ultrasonic tuning of orthopedic bone preparation and bonepreparation instruments and implements.

An embodiment of bandwidth ultrasonic tuning may employ piezo elementsas described herein for production of the desired vibratory motion(s).These elements may be arranged in one, two, or three differentorthogonal planes to produce any combination of superimposed drivenvibrations that may be superimposed on orthopedic instruments and bonepreparation implements.

Some studies of orthogonal bone machining and shallow depths of cut pertooth encountered in sagittal sawing, suggest that a specific cuttingenergy during bone sawing is expected to be quite high.

Therefore, it may be the case that a significant axial/forward thrustforce will be required to cause a saw blade tooth to plunge into asurface of a bone being resectioned, rather than simply riding along thebone surface and causing frictional heating. There may be a tight windowof operation where a sufficient dynamic thrust force is required toinitiate bone chipping, but not so aggressive as to promote reboundingof the blade from the workpiece. With the shallow depths of cutexperienced in sawing, the inhomogeneous microstructure of bone is ofsome interest as it may affect an ability of a tooth of a saw blade orrigid chipping element of other bone preparation implements to penetratethe surface of the bone at the bone preparation site.

In some models, a microstructure of bone may be viewed as more analogousto wood than metal, with cortical bone osteons aligned parallel to anaxis of a long bone just as wood fibers are aligned parallel to the axisof a tree trunk. The orientation of osteons has an effect on bonecutting rates and forces not unlike that experienced when ripping orcrosscutting wood. Osteons in cortical bone are approximately 50 lm to400 lm in diameter, which is approximately an order of magnitude greaterthan depths of cut per tooth experienced in sagittal sawing. Therefore,knowledge of factors that may influence chip creation under particularconditions when cutting osteons may be important to understandingimproved sawing and preparation of cortical bones.

A DOE approach was pursued by Yeager et al. to study the effect of boneorientation on cutting forces at various depths of cut. It was concludedthat sample orientation, relative to the primary osteon direction, anddepth of cut were statistically significant factors influencing cuttingforces. Using an electron microscope to examine the surface of freshlycut bone, the authors observed severe deformation, described as“crushed,” when cutting with negative rake angle tools. They concludedthat under these circumstances, bone debris was formed through thefracture of osteons. Since saw blade teeth normally have negative rakeangles, i.e., the teeth are symmetrical and designed to cut in bothdirections, saw blade teeth may facilitate osteon cracking duringcutting.

Sugita and Mitsuishi observed cracks forming along osteon boundarieswhile viewing transverse cutting of bovine cortical bone under highmagnification. From their microscopic observations of bone fracturing,they proposed a machining method whereby the cutting edge is forced intothe surface of the bone and then concurrently advanced and lifted tocreate chips due to fracturing between and across osteons. The cuttingmotion proposed by Sugita and Mitsuishi is similar to that produced bythe new sagittal sawing device with figure-eight orbital blade motion.

Correlation between the shape of the figure-eight blade path and thetemperature in the surrounding bone is fertile ground for additionalresearch. While the cutting rate of cortical bone with an orbital bladetrajectory was shown to be greater than the cutting rate withtraditional oscillatory blade motion, this does not immediately supportthe conjecture that greater cutting rates produce lower cuttingtemperatures. The creation of larger chips may carry more heat away fromthe cutting zone as hypothesized, but there is also more work being doneby the blade in the cutting zone and this could produce additionalheating.

The following references provide additional information that may berelated to one or more of the embodiments and variations thereof, thesereferences are expressly incorporated by reference for all purposes:

-   T. James et al., “Effect of applied force and blade speed on    histopathology of bone during resection by sagittal saw” Medical    Engineering & Physics 36 (2014) 364-370;-   T. James et al., “Sagittal Bone Saw With Orbital Blade Motion for    Improved Cutting Efficiency” Journal of Medical Devices March 2013,    Vol. 7/011009-1, Downloaded From:    http://medicaldevices.asmedigitalcollection.asme.org/ on Oct. 28,    2013;-   “Piezo Motion Control Tutorial—Why All Piezo Motors are NOT Created    Equal”—accessible from    www.pi-usa.us/en/products/piezo-motors-stages-actuators/piezo-motion-control-tutorial;-   J. Xu et al., “Ultrasonic Vibration Spindle Key Components Design    and Dynamics Analysis”, Proceedings of 2014 IEEE International    Conference of Mechantronics and Automation, August 3-6, available    from    www.pi-usa.us/en/products/piezo-motors-stages-actuators/piezo-motion-control-tutorial;-   D. Zhu et al., “Improving Output Power of Piezoelectric Energy    Harvesters using Multilayer Structures” Procedia Engineering    25 (2011) 199-202;-   K. Vivekanandaa et al., “Design and Analysis of Ultrasonic Vibratory    Tool (UVT) using FEM, and Experimental study on Ultrasonic    Vibration-assisted Turning (UAT)” Procedia Engineering 97 (2014)    1178-1186;-   A. Troedhanl et al., “Cutting bone with drills, burs, lasers and    piezotomes: A comprehensive systematic review and recommendations    for the clinician” International Journal of Oral and Craniofacial    Science, published 14 Aug. 2017;-   C. Laurenczy et al., “Ultrasonic Press-Fitting: A New Assembly    Technique” IPAS 2014, IFIP AICT 435, pp. 22-29, 2014;-   D. Richards et al., “Ultrasonically assisted cutting blades for    large bone surgeries” Sixth International Congress on Ultrasonics,    Honolulu, Hi., USA, 18-20 Dec. 2017, Published by the Acoustical    Society of America © 2018 Acoustical Society of America.    doi.org/10.1121/2.0000752 Proceedings of Meetings on Acoustics, Vol.    32, 030020 (2018)

The system and methods above have been described in general terms as anaid to understanding details of preferred embodiments of the presentinvention. In the description herein, numerous specific details areprovided, such as examples of components and/or methods, to provide athorough understanding of embodiments of the present invention. Somefeatures and benefits of the present invention are realized in suchmodes and are not required in every case. One skilled in the relevantart will recognize, however, that an embodiment of the invention can bepracticed without one or more of the specific details, or with otherapparatus, systems, assemblies, methods, components, materials, parts,and/or the like. In other instances, well-known structures, materials,or operations are not specifically shown or described in detail to avoidobscuring aspects of embodiments of the present invention.

Reference throughout this specification to “one embodiment”, “anembodiment”, or “a specific embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention and notnecessarily in all embodiments. Thus, respective appearances of thephrases “in one embodiment”, “in an embodiment”, or “in a specificembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics of any specificembodiment of the present invention may be combined in any suitablemanner with one or more other embodiments. It is to be understood thatother variations and modifications of the embodiments of the presentinvention described and illustrated herein are possible in light of theteachings herein and are to be considered as part of the spirit andscope of the present invention.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Combinations of components or steps will also beconsidered as being noted, where terminology is foreseen as renderingthe ability to separate or combine is unclear.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the Abstract, is not intendedto be exhaustive or to limit the invention to the precise formsdisclosed herein. While specific embodiments of, and examples for, theinvention are described herein for illustrative purposes only, variousequivalent modifications are possible within the spirit and scope of thepresent invention, as those skilled in the relevant art will recognizeand appreciate. As indicated, these modifications may be made to thepresent invention in light of the foregoing description of illustratedembodiments of the present invention and are to be included within thespirit and scope of the present invention.

Thus, while the present invention has been described herein withreference to particular embodiments thereof, a latitude of modification,various changes and substitutions are intended in the foregoingdisclosures, and it will be appreciated that in some instances somefeatures of embodiments of the invention will be employed without acorresponding use of other features without departing from the scope andspirit of the invention as set forth. Therefore, many modifications maybe made to adapt a particular situation or material to the essentialscope and spirit of the present invention. It is intended that theinvention not be limited to the particular terms used in followingclaims and/or to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include any and all embodiments and equivalents falling within thescope of the appended claims. Thus, the scope of the invention is to bedetermined solely by the appended claims.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A bone preparation tool preparing an in-patientbone with a primary motion in a primary mode of freedom of motion,comprising: a bone-processing implement configured to process thein-patient bone with the primary motion in the primary mode of freedomof motion; an adapter configured to engage and to secure saidbone-processing implement; and a driver, coupled to said adapter,configured to operate said bone-processing implement by use of saidadapter, said driver operating said bone-processing implement in theprimary mode of freedom of motion, said driver configured to operatesaid bone-processing implement in a secondary motion in a secondaryfreedom of motion, and said driver configured to superimpose saidmotions in said modes of freedom of motion producing a superimposedmotion, wherein the primary motion and said secondary motion aresuperimposed by said driver before an application of said superimposedmotion to said bone-processing implement, and wherein one of the primarymotion and secondary motion includes a driven vibratory motion; whereinsaid bone-processing implement includes a saw blade and wherein theprimary mode of freedom of motion includes a sagittal reciprocatingmotion.
 2. The bone preparation tool of claim 1 wherein said driverincludes a set of two or more coupled driver components.
 3. The bonepreparation tool of claim 2 wherein said set of two or more coupleddriver components include a pair of series-coupled driver components. 4.The bone preparation tool of claim 2 wherein said set of two or morecoupled driver components include a pair of parallel-coupled drivercomponents.
 5. The bone preparation tool of claim 2 wherein said set oftwo or more coupled driver components include a pair of hybrid-coupleddriver components.
 6. The bone preparation tool of claim 2 wherein afirst one of said coupled driver components produces the primary motionin the primary mode of freedom of motion, wherein a second one of saidcoupled driver components produces said secondary motion in saidsecondary mode of freedom of motion, and wherein said second one drivercomponent is different from said first one driver component.
 7. The bonepreparation tool of claim 3 wherein a first one of said coupled drivercomponents produces the primary motion in the primary mode of freedom ofmotion, wherein a second one of said coupled driver components producessaid secondary motion in said secondary mode of freedom of motion, andwherein said second one driver component is different from said firstone driver component.
 8. The bone preparation tool of claim 4 wherein afirst one of said coupled driver components produces the primary motionin the primary mode of freedom of motion, wherein a second one of saidcoupled driver components produces said secondary motion in saidsecondary mode of freedom of motion, and wherein said second one drivercomponent is different from said first one driver component.
 9. The bonepreparation tool of claim 5 wherein a first one of said coupled drivercomponents produces the primary motion in the primary mode of freedom ofmotion, wherein a second one of said coupled driver components producessaid secondary motion in said secondary mode of freedom of motion, andwherein said second one driver component is different from said firstone driver component.
 10. The bone preparation tool of claim 1 whereinone of the primary motion and said secondary motion includes a subsonicmotion.
 11. The bone preparation tool of claim 1 wherein one of theprimary motion and said secondary motion includes an ultrasonic motion.12. The bone preparation tool of claim 10 wherein one of the primarymotion and said secondary motion includes an ultrasonic motion.
 13. Thebone preparation tool of claim 1 wherein said driver is responsive to aset of control signals to define and implement one or more of saidmotions further comprising a controller, coupled to said driver,configured to produce said set of control signals.
 14. The bonepreparation tool of claim 13 wherein the primary motion produces a bonepreparation action, wherein the in-patient bone includes a set ofarrangements of osteons, wherein said sets of arrangements of osteonsdefine an influence for said bone preparation action with a first onearrangement of said set of arrangements having a first influence on saidbone preparation action and with a second one arrangement of said set ofarrangements having a second influence on said bone preparation actiondifferent from said first influence, and wherein said controller isconfigured to modify said set of control signals responsive to aparticular one of said arrangements and configured to tune said motionswith a set of tuned motions, said set of tuned motions including a firsttuned motion and including a second tuned motion different from saidfirst tuned motion; wherein said first tuned motion performs said bonepreparation action on said first arrangement with a first tunedperformance metric and performs said bone preparation action on saidsecond arrangement with a second tuned performance metric; wherein saidsecond tuned motion performs said bone preparation action on said firstarrangement with a third tuned performance metric and performs said bonepreparation action on said second arrangement with a fourth tunedperformance metric; wherein said first tuned metric is greater than saidthird tuned metric; and wherein said second tuned metric is less thansaid fourth tuned metric.
 15. The bone preparation tool of claim 14wherein said performance metric includes one or more metrics selectedfrom a group consisting of bone preparation time, bone preparation heatgeneration, bone preparation smoothness, bone resectioning time, orother bone preparation efficiency metric, and combinations thereof. 16.The bone preparation tool of claim 14 wherein said first arrangementincludes a first in-patient bone, wherein said second arrangementincludes a second in-patient bone different from said first in-patientbone, and wherein said tuned metrics include a time for resectioningsaid in-patient bone.
 17. The bone preparation tool of claim 1 whereinsaid freedoms of motion include one or more displacements or rotationsin a lateral (X) plane, a sagittal (Y) plane, and/or an axial (Z) plane.18. The bone preparation tool of claim 17 wherein the primary motionincludes a motion component in a freedom of motion shared with a motioncomponent of said secondary motion.
 19. The bone preparation tool ofclaim 17 wherein the primary motion includes a motion component in afreedom of motion not shared with a motion component of said secondarymotion.
 20. The bone preparation tool of claim 13 wherein the in-patientbone includes a femur, wherein the primary motion includes an axialmotion having an axial amplitude about 100 μm.
 21. The bone preparationtool of claim 1 wherein said bone processing implement includes a fluidchannel configured to receive a fluid, said fluid channel directing saidfluid to a portion of said bone processing implement.
 22. The bonepreparation tool of claim 21 wherein said saw blade includes a cuttingedge and wherein said portion of said saw blade includes said cuttingedge.
 23. The bone preparation tool of claim 21 further comprising afluid reservoir and a fluid conduit coupling said fluid reservoir tosaid fluid channel.
 24. The bone preparation tool of claim 22 furthercomprising a fluid reservoir and a fluid conduit coupling said fluidreservoir to said fluid channel.
 25. The bone preparation tool of claim23 further comprising a temperature sensor configured for direct orindirect measurement of a temperature of the in-patient bone during apreparation of the in-patient bone with said bone processing implementusing the motions and wherein said fluid reduces said temperature whensaid fluid is applied to said fluid channel.
 26. The bone preparationtool of claim 23 further comprising a temperature sensor configured fordirect or indirect measurement of a temperature of said bone preparationimplement during a preparation of the in-patient bone with said boneprocessing implement using the motions and wherein said fluid reducessaid temperature when said fluid is applied to said fluid channel.
 27. Amethod for operating a bone preparation tool configured for preparationof an in-patient bone, comprising: producing a primary motion in aprimary mode of freedom of motion; producing a secondary motion in asecondary mode of freedom of motion; superimposing said motions togetherproducing a superimposed motion; and applying said superimposed motionto a bone preparation implement of the bone preparation tool; andwherein said superimposed motion includes a driven vibratory motion;wherein said bone preparation implement includes a saw blade; andwherein the primary mode of freedom of motion includes a sagittalreciprocating motion.